1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, more particularly, a method for, manufacturing a semiconductor device using a silicon carbide substrate.
2. Description of the Background Art
In recent years, in order to achieve high breakdown voltage, low loss, and utilization of semiconductor devices under a high temperature environment, silicon carbide has begun to be adopted as a material for a semiconductor device. Silicon carbide is a wide band gap semiconductor having a band gap larger than that of silicon, which has been conventionally widely used as a material for semiconductor devices. Hence, by adopting silicon carbide as a material for a semiconductor device, the semiconductor device can have a high breakdown voltage, reduced on-resistance, and the like. Further, the semiconductor device thus adopting silicon carbide as its material has characteristics less deteriorated even under a high temperature environment than those of a semiconductor device adopting silicon as its material, advantageously.
An exemplary, known method for manufacturing such a semiconductor device adopting silicon carbide as its material is to form an epitaxial growth layer on a silicon carbide substrate, then introduce an impurity by means of ion implantation, form an electrode, and the like. In this way, a silicon carbide semiconductor device achieving a desired operation can be obtained (for example, see Japanese Patent Laying-Open No. 2010-103229).
However, the following problem can take place when adopting silicon carbide as a material for a semiconductor device. That is, a general manufacturing facility for semiconductor devices is configured to use a silicon substrate. For improved manufacturing efficiency, the substrate is usually conveyed and set automatically in each manufacturing process. Whether or not the substrate is set at a desired location in each manufacturing process is confirmed by, for example, applying light such as laser to the location in which the substrate is supposed to be set, and detecting interception or reflection of the light by the substrate by means of a sensor. Meanwhile, the silicon carbide substrate is greatly different from the silicon substrate in light transmittance and reflectance. More specifically, the silicon substrate has a low light transmittance, whereas the silicon carbide substrate is almost transparent and therefore has a significantly higher light transmittance than that of the silicon substrate.
Under such a circumstance, if the above-described general manufacturing facility is employed to manufacture a semiconductor device using a silicon carbide substrate, conveyance and setting of the silicon carbide substrate are not recognized correctly. This hinders automated conveyance and setting of the substrate. To address this, a light source or a sensor used for the recognition of substrate is changed to handle the silicon carbide substrate, thus overcoming the above-described problem. However, the recognition of substrate is required whenever a substrate is conveyed in the manufacturing facility for the semiconductor device. Hence, in order to accommodate the manufacturing facility to the silicon carbide substrate, the manufacturing facility needs to be modified drastically. This results in increased facility cost, which leads to increased manufacturing cost of the semiconductor device, disadvantageously.